Lacosamide is an anticonvulsive which has been approved in several countries for the adjunctive treatment of partial-onset seizures in adults. Lacosamide is thought to work by selective enhancement of sodium channel slow inactivation and demonstrated efficacy and good tolerability in clinical trials. Lacosamide is available in the form of immediate release tablets, oral solutions and intravenous injection solutions. Tablets are approved as 50 to 200 mg dosage units for twice daily administration, and after such administration result in maximum dosage-normalized lacosamide steady state plasma levels (Cmax, ss, norm) of about 40-43 ng/ml/mg in a population of an average distribution volume of 50 liters. Tmax is usually reached within 1.4-1.5 hours after administration. Lacosamide has a solubility in water of about 27 g/L, and is rapidly and completely absorbed by the animal body substantially following a first order kinetic. Lacosamide has an elimination half-life of about 13 to 14 hours, making it an ideal candidate for a twice daily immediate release formulation. No modified release formulations of lacosamide are known so far.
State of the art lacosamide formulations are immediate release formulations. Such formulations are commercialized as “Vimpat®” tablets, having a tablet core consisting of 200 mg lacosamide as the active agent, 40 mg crospovidone as a disintegration agent, 56 mg microcrystalline cellulose type 102, 50 mg hydroxypropylcellulose (low substituted), 4 mg hydroxypropylcellulose, 125.2 mg silicified microcrystalline cellulose as fillers and binders, and 4.8 mg magnesium stearate as a lubricant. The tablets have a non-functional coating. This tablet releases 98% of the active agent within 15 minutes after contact with an aqueous medium.